This project studies gene therapy for chronic granulomatous diseases (CGD) and other inherited immune diseases affecting human phagocytes, and also studies use of gene therapy to augment phagocyte host defense against chronic intracellular infections such as tuberculosis and other mycobacterial infections. CGD are a group of 4 distinct genetic disorders with common phenotype characterized by life-threatening recurrent infections caused by failure of blood neutrophils and monocytes to produce superoxide and hydrogen peroxide. CGD results from the failure to produce any of the components of the NADPH oxidase. We have achieved retrovirus mediated gene transfer to functionally correct 3 genetic forms of CGD by transfer of normal oxidase genes into cultured hematopoietic progenitor cells. The target cells are marrow-like myeloid progenitor cells which can be harvested from the peripheral blood resulting in 1% to 20% correction of superoxide production by phagocytes differentiated from CGD progenitors transduced with normal oxidase gene. Work is in progress to build on these accomplishments to develop a clinical protocol of gene therapy for CGD. Several host defense genes have been cloned which may play a role in host resistance to intracellular pathogens responsible for certain indolent infections such as tuberculosis. Nitric oxide synthase producing nitric oxide in murine macrophages appears to be important for control of intracellular pathogens such as tuberculosis, though this host defense mechanism is not firmly established in human phagocytes. We have achieved constituitive expression of murine macrophage NOS gene in human macrophage cells lines with resultant constant production of nitric oxide. This will be an important model to test the hypothesis of the potential host defense utility of nitric oxide production by human phagocytes.